645857679 has 4 divisors (see below), whose sum is σ = 861143576. Its totient is φ = 430571784.

The previous prime is 645857657. The next prime is 645857699. The reversal of 645857679 is 976758546.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 645857679 - 2⁷ = 645857551 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645857609) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 107642944 + ... + 107642949.

It is an arithmetic number, because the mean of its divisors is an integer number (215285894).

Almost surely, 2^645857679 is an apocalyptic number.

645857679 is a deficient number, since it is larger than the sum of its proper divisors (215285897).

645857679 is a wasteful number, since it uses less digits than its factorization.

645857679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215285896.

The product of its digits is 12700800, while the sum is 57.

The square root of 645857679 is about 25413.7301276298. The cubic root of 645857679 is about 864.3950592279.

The spelling of 645857679 in words is "six hundred forty-five million, eight hundred fifty-seven thousand, six hundred seventy-nine".